The semiconductor integrated circuit (IC) industry has experienced rapid growth. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs. Such scaling down has also increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC manufacturing are needed.
As IC technologies are continually progressing to smaller technology nodes, simply scaling down similar designs used at larger nodes often results in inaccurate or poorly shaped device features. For example, rounded corners on a device feature that is designed to have right-angle corners may become more pronounced or more critical in the smaller nodes, preventing the device from performing as desired. Other examples of inaccurate or poorly shaped device features include pinching, necking, bridging, dishing, erosion, metal line thickness variations, and other characteristics that affect device performance.
Typically, optical proximity correction (OPC) may be performed on a design pattern to help alleviate some of these difficulties before the design pattern is used in later operations in an IC manufacturing process, such as an operation creating a mask or a photolithography process exposing wafers. OPC may modify shapes of the design pattern and/or insert assist features (AF) based on simulated IC manufacturing processes. Improvements in an IC manufacturing process involving OPC are desired.